The measuring method with the microwave is adopted in the noncontact conductivity measurement of a silicon wafer (see Non-Patent Reference 1 and Patent Reference 1). The noncontact measurement can be realized by using the microwave which can propagate through air. The microwave has an advantage that reaction of the microwave is directly associated with electric properties of a sample.
However, currently there is no instrument dedicated to the sample measurement with the microwave, and a network analyzer which measures an S parameter of a passive and active network of an electronic instrument is usually used as an alternative to the dedicated instrument. Because the network analyzer is large and expensive, it is difficult that the network analyzer is used as an industrial instrument.
Non-Patent Reference 1: Ju, Y., Inoue, K., Saka, M., and Abe, H., Contactless measurement of electrical conductivity of semiconductor wafers using the reflection of millimeter waves, Journal of Applied Physics Letters, Vol. 81n19, 2002, pp. 3585-3587
Patent Reference 1: Japanese Patent Laid-Open No. 2004-177274